Ambari - Operating System matching redhat7 could not be found

After upgrading from Ambari 2.5.0.3 to 2.6.2.2, ambari-server.log file suddenly start recording following entries:

28 Nov 2020 16:48:52,372  WARN [ambari-action-scheduler] ActionScheduler:316 - Exception received
java.lang.RuntimeException: org.apache.ambari.server.controller.spi.SystemException: Operating System matching redhat7 could not be found
        at org.apache.ambari.server.actionmanager.ExecutionCommandWrapper.getExecutionCommand(ExecutionCommandWrapper.java:253)
        at org.apache.ambari.server.actionmanager.ActionScheduler.processInProgressStage(ActionScheduler.java:704)
        at org.apache.ambari.server.actionmanager.ActionScheduler.doWork(ActionScheduler.java:417)
        at org.apache.ambari.server.actionmanager.ActionScheduler.run(ActionScheduler.java:310)
        at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.ambari.server.controller.spi.SystemException: Operating System matching redhat7 could not be found
        at org.apache.ambari.server.state.stack.upgrade.RepositoryVersionHelper.getOSEntityForHost(RepositoryVersionHelper.java:422)
        at org.apache.ambari.server.actionmanager.ExecutionCommandWrapper.getExecutionCommand(ExecutionCommandWrapper.java:247)
        ... 4 more

Server's OS has always been RedHat 7.x and prior to the upgrade there were no issues with the OS version:

$ cat /etc/redhat-release
Red Hat Enterprise Linux Server release 7.5 (Maipo)

To make this more interesting, Ambari WebUI in the hosts details correctly identifies the OS version

OS: redhat7 (x86_64)

Ambari WebUI and `ambari-server --version` already show upgraded version `2.6.2.2`.

Please help solve this issue.